docs: def load_libdmtx():
      """Loads the libdmtx shared library.
  
      Populates the globals LIBDMTX and EXTERNAL_DEPENDENCIES.
      """
      global LIBDMTX
      global EXTERNAL_DEPENDENCIES
      if not LIBDMTX:
          LIBDMTX = dmtx_library.load()
          EXTERNAL_DEPENDENCIES = [LIBDMTX]
  
      return LIBDMTX